I suppose I should add here that while antihystamines were a great option for poeple who suffered from allergies, the medicine made you tired. It's a great medicine for when you're feeling sick and really need it, but it can be tricky if you have the medicine in your system and you're trying to get through the day. How do you work when you're tired? How do you take care of kids? It's possible, but not any fun.
An important development came in 1953 with the discovery of the mast cell. This is a cell involved in the immune response that carries histamine, later referred to as a mediator of inflammation because it causes the inflammation that results in the allergy symptoms.
In 1967 Immunoglobulin E antibodies (IgE) were discovered. It was later learned IgE have a significant role in the allergic response. The first time an allergic person is exposed to an allergen, say dust mites, his immune system develops dust mite IgE antibodies that attach to mast cells that line the epithelial layer of the skin or respiratory tract.
The second time that person is exposed to that allergen (dust mites in this case), a mast cell that
has a dust mite IgE antibody attached to it explodes and releases its contents, the mediators of inflammation. Other mediators eventually discovered include histamine, cytokines and leukotrienes.
It's actually these mediators that cause the inflammation around the eyes, inside the nose, throat, bronchioles, and/or on the skin. The result then would by your typical hay fever or allergy symptoms, asthma, hives, or excema.
By the late 1970s it was learned that leukotrienes were the main culprits in causing inflammation of the bronchioles. By 1980 leukotriene antagonists were discovered and proven to block the effects of leukotrienes. By the early 2000s leukotriene antagonists such as Singulair were on the market and available for the treatment of allergic asthma.
In 2003 the FDA approved Xolair to treat allergy related asthma. It was the first medicine approved that inhibited the effects of IgE. It's still a new drug on the market and opinions continue to vary on its efficacy. The fact this medicine costs thousands of dollars per dose might have something to do with this opinion.
Like asthma, allergies continue to perplex the scientific and medical community. Despite modern wisdom, the best treatment continues to be avoidance of allergens, a task that's much easier said than done.